What’s the Difference Between an SDK and an API?

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Consumers have come to expect digital experiences from their favorite brands. The most common way that companies achieve this is by developing an app or website. These mediums are powerful ways to connect with customers and take advantage of how connected today’s consumers are to the internet.

If you are looking to develop an app or add features to your website, you might want to consider working with a developer to help you make those changes. But, in order to bring that digital experience to life, it’s important to understand the process on the back end.

When developing an app or adding features to your website, SDK and API are two terms you often hear when discussing how to integrate different systems. A common misconception is that you have to decide whether to use either an SDK or an API. In reality, SDKs and APIs are bound to overlap, which makes comparing them — or choosing between them — a bit confusing. There are situations where the best solution includes both.

If you’re beginning to outline the process for building your digital experience, start here to understand what an SDK and an API are, how they differ, and how to utilize them.

What is an API?

An application programming interface (API) is a set of protocols and tools for building application software. It is a set of clearly defined methods of communication between various software components. Most companies, especially tech companies, have built APIs for their customers or for internal use.

Say you own a salon and your business has a website. On that website you have a form where clients can sign up for appointments and then create a Google Calendar event with all the details for their appointment.

Your API comes in when your website’s server communicates with Google’s server to create an event with all of those details. In relation to customer experience, it is the API that allows customers to create the calendar invite without leaving your website.

What is an SDK?

A software development kit (SDK) is a set of software development tools that allows the creation of applications for a certain software package, software framework, hardware platform, computer system, video game console, operating system, or similar development platform.

To put it simply, an SDK is a tool box that often includes APIs, pieces of code, or other rules for developing software. Companies make their SDKs available to developers in order to help them easily integrate with their services.

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What’s the difference between an SDK and an API?

There isn’t a simple answer to how an SDK and an API differ, because SDKs commonly contain an API.
When a developer uses an SDK to create systems and develop applications, those applications need to communicate with other applications. An SDK includes an API to make that communication possible. On the other hand, while the API can be used for the communication, it cannot create a brand-new application.

The real difference is that an API is really just an interface for a service, while an SDK is the tools/components/code fragments that have been created for a specific purpose.

If you’ve ever done an online search for a cake recipe, you’ve likely noticed that a lot of companies make their recipes available online free. This is not unlike software companies that provide their API online for programmers to use.

If you like to mix things up (no pun intended) when you’re baking and incorporate other recipes, that can be compared to incorporating different APIs into your application to provide different features.

Sometimes you don’t feel like baking a cake from scratch. Or you have your sights set on a triple-tier cake, and you just don’t have the skills to bake it. In those instances, a premade cake mix is your go-to.

A premade cake mix provides you with the main ingredients, already measured out, and only requires you to add one or two additional ingredients before you bake and serve. That is, in the simplest terms, what an SDK is.

Without either, you would need to start at the beginning and write the code for your project.

Do you have to choose?

Simply put, the answer is no, you do not have to choose between an SDK and an API.

There are different instances in which you may decide to build an API or use a provided API, and there are times when you may want to use a provided SDK that includes one or multiple APIs.

For example, with web development, you need to identify which features you want to implement into your website and then identify which APIs you need to make those features come to fruition. Once you’ve decided that, you need to decide if you want to use a company’s provided SDK, which often includes the API along with other tools, documentation, and code samples.

It may sound overwhelming, but the first thing to do is decide where you want to start, understand the best approach, and identify what your end goal is. Depending on that, your decision can affect your experience, the user experience, reliability, and the timeline. Each integration and program is different, so you need to weigh the pros and cons of different areas like expertise needed to integrate, time to market, security, cost, and reliability.

When creating your software or application, just remember:

SDKs usually contain APIs, but APIs do not contain SDKs.

SDKs enable developers to create applications and act as the building blocks for your software solution.

APIs enable the function of applications within the parameters of the SDK with which they are bundled.

Where to start when hiring a developer

Now that you know some of the terminology and how APIs and SDKs work together, you may decide to start working with a developer to build out your website or app. This person can help you identify which APIs are needed to achieve your vision, how much those APIs cost to use, how they affect how your website runs, and the best plan of action to implement them.

For your website, look for someone who at a minimum knows HTML and CSS. Look at their portfolio and examples of other websites they have built for reference. If you don’t want to write the content for the website, look for someone who understands copywriting and search engine optimization (SEO).

If you’re looking for an app developer, the type of coding knowledge to look for will vary depending on the app platform for which you are creating an app (Android or iOS). In addition to being functional, your app should be enjoyable for your customers to use. Look for a developer who has a portfolio of past experience that includes user experience (UX) or user interface (UI) skills.

Before making a decision, ask for references so you can contact past clients and get feedback on their work.